I just changed the plugs for the first time on my 740 and as I got to the last 2 closest to the firewall they had oil on them. It seemed to be on the nut part of the plug as well as the wall where the plugs go in (16v GLE). Could this be a problem. I have no misfires and those plugs were not any more fouled the the other 2.
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1988 245 340,000 Kms , 1990 740 GLE 16V 220,000 Kms

On the plus side, a little bit of oil in the plug hole helps to keep the threads from seizing up. "That's a feature, not a flaw" :-)

Bill

Many 16v have that problem, mine too. The leak of oil is a failure of the gasket in the cam carrier. Probably the O rings where the cam carrier rests on the head.
Not an easy job but not impossible. Best to do when changing the timing belt.
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744 & 745 GLE's (IPD a-sbars)16v M46, 245 SE(IPD a-sbars) auto, 242Ti M46(IPD springs and bars), 745GL 8v auto

As you mention, it's a common problem, but I think you'll find it's a failure of the inner valve cover gasket (it seals around the plug recesses) that allows the oil to weep into the plug recesses and foul the base of the plugs, sometimes to the point of baking oil onto the plug ceramic and even contaminating the end of the spark plug boot. A plugged PCV system can aggravate the problem as can an improperly torqued and sealed valve cover. Just wipe out the plug recesses regularly until you get a chance to properly deal with the leak.
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Dave -940's, prev 740/240/140/120 Never overestimate what little I know.

You may be right I can't remember. Replacing the valve cover gaskets (the one at the edge and the one around the plug holes) , is pretty easy.
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744 & 745 GLE's (IPD a-sbars)16v M46, 245 SE(IPD a-sbars) auto, 242Ti M46(IPD springs and bars), 745GL 8v auto